A computer pointing device, generally referred to as a mouse, is one of the most commonly used devices for computer interface devices. A user moves the mouse on a surface. A motion sensing mechanism in the mouse senses the motion and moves a cursor on the computer display accordingly. There are generally two types of motion sensing mechanisms, mechanical motion sensing and optical motion sensing.
A mechanical motion sensing mechanism generally includes a tracking ball at the bottom of the mouse and mechanically coupled to two tracking wheels. When the mouse moves on a surface, e.g., a mouse pad or desk surface, the rolling ball rolls. The tracking wheels convert the rolling motion of the rolling ball into electrical signals to control the movement of a cursor on the computer display. A mechanical motion sensing mouse is susceptible to damage and performance deterioration resulting from dirt accumulation and wear.
An optical motion sensing mechanism generally includes a light emitting device, e.g., a light emitting diode and an array of photo detectors. The array of photo detectors senses a light beam emitted from the light emitting device and reflected by a surface under the mouse. As the user moves the mouse over the surface, features on the surface, e.g., colors, textures, reflectivity, in different regions of the surface, move relative to the array of photo detectors. The photo detector array senses the reflected light beam and decodes the mouse motion with respect to the surface from the light beam variation. In an optical mouse, the light emitting device is a major power consumption element. For a wireless mouse, the light emitting device may be a predominant factor determining the battery life.
Accordingly, it would be advantageous to have a computer pointing device, e.g., a mouse, having a power efficient motion sensing mechanism. It is desirable for motion sensing mechanism to be reliable. It is also desirable for the mouse to have high performance. It is of further advantage for the mouse be simple, convenient to use, and cost efficient.